* Techie translation: BSNS is a simple YAML content store to allow your boss to tweak the website himself just by using a text editor. Assuming you then keep all of those changes in version control, you end up with a log of all changes and who was responsible for them.

Your boss, Jim, he's a genius. A true sandwich artist. He spends a lot of time making up new sandwiches, or tweaking the old classics. Really, he doesn't get that many customers, so he has a lot of free time on his hands.

He wants you to make a new website for the restaurant, one that's dynamic and changes as often as the menu does.

"No problem," you say. "Gimme a couple of weeks and a ton of Mountain Dew."

Installation is dead-simple, you just type:

gem install bsns

And for good measure, you add this line to your Gemfile:

gem 'bsns'

Now you just make a new directory in your app root called "bsns_content" and add this line of code somewhere in your initialization scripts (those are the scripts that load when your application loads).

require 'bsns'
BSNS.configure :content_path => File.dirname(__FILE__) + 'bsns_content'

Now you make a model for sandwiches. It looks something like this:

class Sandwich < BSNS::Base

	attr_accessor :name, :description

	has_many :ingredients, :with => :amount

end

For each sandwich that Jim creates, you tell him to add a file within bsns_content/sandwiches.

For example, the ham sandwich might end up in bsns_content/sandwiches/ham.yml, and might look something like this:

title: Ham Sandwich
description: Breakfast on a bun!  This ham sandwich features seasoned eggs, the
finest slices of American cheese, and a dash of olive oil on a wheat roll.
ingredients:
  ham: 2
  american_cheese: 2
  scrambled_egg: 2
  olive_oil: 1
  avocado: .5

And you make a second model for Ingredients, which you're fine placing all into one file.

class Ingredient < BSNS::Base

	acts_as_collection

	attr_accessor :name, :cost

end

Your YML file (bsns_content/ingredients.yml) might look something like this:

american_cheese: 
  title: American Cheese
  cost: 5
  description: a slice of American cheese
  calories: 50
ham:
  title: Thickly-sliced Ham
  cost: 68
  description: Some people would call it Canadian bacon.
  calories: 100
scrambled_egg:
  name: Scrambled Eggs
  cost: 42
  description: jumbo Grade-A egg, scrambled with salt, chives, and a touch of butter.
  calories: 50
wheat_roll:
  name: Wheat Roll
  cost: 15
  description: a freshly-baked wheat roll
  calories: 60
olive_oil:
  name: Olive Oil
  cost: 5
  description: a dash of olive oil
  calories: 20
avocado:
  name: Avocado
  cost: 100
  description: Premium California Haas Avocados, grown by a mystical race of green-thumbed gnomes who work for candy corn instead of wages.
  calories: 600
banana:
  name: Banana
  cost: 18
  description: A full banana.
honey:
  name: Honey
  cost: 4
  description: A spread of honey.
peanut_butter:
  name: Peanut Butter (smooth)
  cost: 20
  description: A spread of peanut butter.

Now you can do fun stuff with your models. Let's add a method to Sandwich to automatically price sandwiches at a 150% markup.

class Sandwich < BSNS::Base

	def price
	    total = 0
		ingredients.each do |i|
		  total = total + i.cost*i.amount
		end
		total * 1.5
	end

end

But this puts you in the position where you're responsible for changing the code every time Jim wants to tweak the margin on sandwiches! Plus, what happens when you end up with a crate full of bananas and nobody's touching the PB&B sandwiches?

What if we made it possible for Jim to set a sound default price modifier for all sandwiches, and then let him override those defaults later? (Yes, I know, this sounds an awful lot like programming, but don't let Jim know that or he'll realize he doesn't need you to be his web developer).

You'd give Jim a new YML file called sandwiches/_defaults.yml. It's what it says on the tin: default values for all sandwiches.

price_modifier: 1.5
description: No description available. :(

And add a new sandwich file, sandiwches/pbnb.yml:

title: Peanut Butter and Banana
ingredients:
  banana: 1
  peanut_butter: 1
  honey: 1
price_modifier: .5

Now, we can change our code to:

class Sandwich < BSNS::Base

	attr_accessor :price_modifier

	def price
	    total = 0
		ingredients.each do |i|
		  total = total + i.cost*i.amount
		end
		total * price_modifier
	end

end